Lath and plaster is a building technique used mainly for interior walls, and ceilings in
period buildings. A lath is a narrow strip of wood which is nailed horizontally to each stud in the frame. Each is
spaced approximately 1/4inch (thickness of the average little finger),
away from the next, leaving enough space for the haired mortar to push
through and hook over the lath to form a key laths.

Preparation
The laths must be free from dirt, grease and vegetation. These elements
should be removed before damaged laths are repaired. Spray a clean
cold water mist on to the laths prior to applying the scratch coat.